pngtools — local PNG cleanup

1 Select PNG

Select a PNG file to start. Processing happens locally in your browser.

Choose PNG file No file selected

Ready for a PNG file.

2 Original preview

Drag on the image to select a cleanup preview area. On a touch screen, tap the top-left corner and then the bottom-right corner. If you do not select one, a center crop is used.

3 Metadata

Complete parsed metadata from the original PNG file.

Scanline filter visualization

Non-interlaced PNG rows are tinted by their stored scanline filter byte while keeping the decoded image visible.

Load a PNG to inspect scanline filters.

NONE `0`	—
SUB `1`	—
UP `2`	—
AVERAGE `3`	—
PAETH `4`	—

4 Cleanup noisy flat colors

This is a tolerant neighborhood cluster filter, not a blur. It changes pixels only when a nearby color cluster strongly agrees and the current color is already close to that cluster.

Live preview

Radius 1 Color threshold 12 Minimum agreeing pixels 4 Iterations 1

Include alpha in distance Process only fully opaque pixels

Selected original region

Live cleanup preview

5 Reduce colors

Generate a small local palette for the current result. Pixels with alpha at or below the cutoff become one transparent entry; all other pixels are quantized as opaque RGB colors for consistent indexed PNG output.

Worker preview

Target colors Algorithm Dithering Transparent alpha cutoff 1 Median-cut sample interval 1Controls palette analysis only: 1 examines every pixel; 2 examines every second pixel; and so on. Higher values are faster but may miss small color details. Every pixel is still mapped to the finished palette.

Preview a reduced palette before applying it to the current result.

Current result

Reduced color preview

6 Rotations

Select an exact rotation for the current result.

7 Resize

Resize the current result while preserving the image ratio. Downscales default to smooth; 2× upscales default to sharp for small-palette artwork and smooth for full-color images.

Algorithm: Smooth Sharp / pixel-perfect

Choose a scale to resize the current result.

8 Remove exterior connected color

Finds the most common exact RGB color along the image edges, then flood-fills only connected pixels close to that color. Interior details of the same color remain intact.

Color tolerance 20 Soft edge feather 0 px

Also crop to the visible bounding box after removal

9 Result preview

Current download: Original image

True-color preview